The invention relates to the filed of a disc changers for storing disc-shaped information carriers and transporting the information carriers into and out of a scanning position.
Commonly an information disc player has a disc changer for storing disc-shaped information carriers and transporting the information carriers into and out of a scanning position. Such a player also has a turntable which is rotatable about an axis of rotation for supporting and rotating an information carrier in the scanning position, and a scanning device for scanning the information carrier in the scanning position.
A disc changer and an information disc player of the kinds mentioned in the opening paragraphs are known from WO 96/34386. The known disc changer is provided in the known information disc player and has a carousel-like support unit for the information carriers. The support unit is rotatable about an axis of rotation by means of an electrical motor and has a number of supporting surfaces for storing and supporting the individual information carriers. The information carriers are transported into and out of the scanning position by rotating the support unit carrying the information carriers about the axis of rotation of the support unit. When an information carrier has been transported into the scanning position, the information carrier is supported by the turntable of the information disc player and is scanned by means of the scanning device of the information disc player by rotating the information carrier about the axis of rotation of the turntable and by displacing a scanning unit of the scanning device in a radial direction relatively to the axis of rotation of the turntable.
The inventor recognizes that disadvantage of the known disc changer and the known information disc player is that the carousel-like support unit constitutes a rather bulky rotatable part of the disc changer having a relatively high moment of inertia. Therefore, the electrical motor for rotating the support unit and transporting the information carriers into and out of the scanning position must be able to exert a relatively high mechanical torque on the support unit.
It is an object of the invention to provide a disc changer and an information disc player of the kinds mentioned in the opening paragraphs, in which the information carriers can be transported into and out of the scanning position by means of a transport device having displaceable parts with a relatively small mass and/or rotatable parts with a relatively small moment of inertia, so that the information carriers can be transported into and out of the scanning position by means of an actuator exerting only a relatively small mechanical force or torque.
To achieve this object, a disc changer in accordance with the invention has a closed stationary guiding track for storing and guiding the information carriers, the guiding track having a transport direction and a width which, viewed in a direction perpendicular to the transport direction, substantially corresponds to a diameter of the information carriers, the guiding track being respectively bounded, viewed in a direction perpendicular to the transport direction, by a rolling track, which is stationary relative to the guiding track for cooperation with a circumferential part of the information carriers, and by a driving member for rolling the information carriers along the rolling track by cooperation with the circumferential part.
An information disc player in accordance with the invention used a disc changer in accordance with the invention.
In the disc changer in accordance with the invention, the information carriers are supported by the stationary guiding track. Since the width of the guiding track substantially corresponds to the diameter of the information carriers, the information carriers fit substantially without any tolerance between the rolling track and the driving member, so that the information carriers can be rolled by the driving member along the rolling track by the cooperation of the driving member with the circumferential parts of the information carriers. Since the guiding track is closed, the guiding track can be substantially completely filled with the information carriers, and the information carriers can be transported relatively to the guiding track in an endless manner and without hindrance in the transport direction or in a direction opposite to the transport direction. Since the guiding track and the rolling track constitute stationary parts of the disc changer, and the driving member constitutes the only displaceable and/or rotatable part of the disc changer, the mass of the displaceable parts and/or the moment of inertia of the rotatable parts of the disc changer are relatively small, so that the information carriers can be transported into and out of the scanning position by means of an actuator exerting only a relatively small mechanical force or torque.
In a particular embodiment of a disc changer in accordance with the invention, the guiding track is annular and the rolling track is circular, the driving member comprising a roller which is rotatable about an axis of rotation substantially coinciding with a common central axis of the guiding track and the rolling track and which is driveable by means of an electrical motor. In this particular embodiment, a very simple construction of the disc changer is achieved. Since the driving member uses the roller, the driving member also has a very simple construction and a very low moment of inertia.
In a further embodiment of a disc changer in accordance with the invention, the roller has an annular supporting surface which extends transversely to the axis of rotation for cooperation with a circumferential part of a main side of the information carriers. Since the roller is provided with the annular supporting surface, the information carriers are rolled along the rolling track mainly by the cooperation of the roller with the circumferential part of the main side of the information carriers, and substantially without any cooperation of the roller with the outer edges of the information carriers. In this way, it is not necessary for the information carriers to fit in a very close manner between the rolling track and the driving member to achieve the necessary cooperation between the information carriers, the rolling track, and the driving member. As a result, the width of the guiding track does not need to be very accurate, and also the loading and unloading of the information carriers into and out of the disc changer is facilitated.
In yet further embodiment of a disc changer in accordance with the invention, the guiding track has an annular supporting surface for cooperation with a main side of the information carriers, and the rolling track has a circular cylindrical rolling surface for cooperation with an outer edge of the information carriers, the supporting surface of the guiding track extending substantially perpendicularly to the axis of rotation and being bounded by the rolling track, the rolling surface of the rolling track extending substantially perpendicularly to the supporting surface of the guiding track. As a result of the cooperation of the rolling surface of the rolling track with the outer edge of the information carriers, good rolling properties of the information carriers along the guiding track without any substantial slip are achieved, so that a reliable operation of the disc changer is achieved. As a result of the cooperation of the rolling surface of the rolling track with the outer edge of the information carriers and the cooperation of the supporting surface of the guiding track with the main side of the information carriers, an accurate position of the information carriers relative to the guiding track is achieved in directions perpendicular to the transport direction.
In a particular embodiment of a disc changer in accordance with the invention is, guiding track and the rolling track are formed by a circular cylindrical recess provided in a main frame of the disc changer, wherein the guiding track is formed by a bottom part of the recess and the rolling track is formed by a side wall of the recess, the roller being rotatably journalled in the bottom part. In this manner, the guiding track and the rolling track are formed in a very simple manner, so that the construction of the disc changer is further simplified.
In a further embodiment of a disc changer in accordance with the invention, the disc changer has a detector system for detecting a presence of an information carrier in the scanning position. In the disc changer in accordance with the invention, it is principally not possible to determine a position of the information carriers in the transport direction relative to the guiding track and the scanning position as a function of a position of the driving member. As a result of the use of the detector system, the presence of an information carrier in the scanning position can be detected independently of the position of the driving member, so that it is possible to detect whether the information carrier is in a correct position to be scanned.
In yet further embodiment of a disc changer in accordance with the invention, the detector system includes two optical detectors which are arranged to detect the circumferential part of an information carrier which is present in the scanning position. As a result of the use of the two optical detectors, a reliable and accurate detection of the presence of an information carrier in the scanning position is achieved.
In a particular embodiment of an information disc player in accordance with the invention, is the guiding track, the rolling track, and the driving member of the disc changer are provided on a drawer of the information disc player which is displaceable from an operational position, in which the drawer has been retracted into a housing of the information disc player, to a loading position, in which the drawer is at least partially outside the housing. In this manner, the loading and unloading of the information carriers into and out of the information disc player is facilitated.
In a further embodiment of an information disc player in accordance with the invention, the guiding track and the rolling track of the disc changer used therein are formed by a circular cylindrical recess provided in a main frame of the disc changer, and the recess of the disc changer is provided in the drawer. In this manner, a very simple construction of the information disc player is achieved.
The invention will be further explained below with reference to the drawing, in which